1. Field of the Invention
The present invention generally relates to a motor equipped with a coil, more particularly, relates to a heat dissipating structure of the motor to dissipate heat generated by the armature.
2. Description of the Related Art
With numerous fans and drive motors for heat dissipation, disk drives, and like applications being installed in electronic devices, high speed motor operation is being demanded, in part because the demand for high speed data transfer and high heat dissipating capacity is increasing. A motor which rotates at a high speed is one answer to this need. In such a motor, however, a large electric current flows into a coil of an armature of the motor, and the coil generates considerable heat. The heat may substantially compromise reliability and endurance of the motor since a copper wire used for the coil has a temperature limit and the generated heat influences bearing life.
A motor having a heat dissipating structure is one answer to the demand for high-speed motor operation. One example of such a structure for an axial fan is to provide outside air into an impeller cup which accommodates a coil via a through hole on an upper surface of the impeller cup. In this structure, however, air which flows into the impeller cup via the through hole is limited. With such limited air flow, only limited heat will be dissipated from the coil of the motor.